I am not at all an artsy-craftsy type, and my google-fu is failing me.
I want to frame four 9 1/2" x 48" posters. Moreover, I want to put some 3D objects inside the frame – specifically, pebbles glued to the poster. I do not want to pay hundreds of dollars for this. I am willing to do some of the work myself if need be.
Help.
Odd-shaped and inexpensive don’t usually go together. You might try to find a frame-it-yourself shop in your area (I used one all the time when I lived in Ann Arbor but that was 25 years ago). They provide instruction, raw materials, tools, and workspace. The depth needed to allow space for the pebbles is probably the biggest hurdle. If you go to a custom framing shop then, yeah, you could be looking at in the hundreds for four of those. I have at least one frame that cost more than the painting in it…
I think you are looking for “Shadow box” type frames. Other frames are going to be too thin. Large craft stores (like Michael’s) can custom-make frames for you.
They may also have pre-made shadow-box type frames for sale - you could get one slightly larger than you need, and cut your own mat for the poster part.
I doubt that the framing shops will have any pre-made frames that are that weird shape. I once wanted to get something framed that was long and short and the frame shop said that the custom glass size would be expensive. In the end, I had them mount it on foamcore.
You can see what they have available at a place like www.framesbymail.com/.
You have to do the work yourself, but it is way cheaper then getting it professionally framed and typically the results are very nice. Again the rub is the depth issue, but you might be OK by substituting the foamcore backing for something less thick.
Look at “canvas” frames - they’re built to hold canvas on wood stretcher frames, so they can hold something about 3/4" thick.
They may be hard to find at the local art and hobby shop, but they’re easy to get from mail order places like Frame Fit, Frames By Mail, etc.